The metacarpophalangeal joints of the second through fifth fingers are synovium-lined condyloid joints characterized by the articulation of the rounded articular surfaces of the metacarpal heads into the shallow concavities of the articular surfaces of the proximal end of the first phalanges (Fig. 79.1). The metacarpophalangeal joint of the thumb is a ginglymoid hinge-type joint. The primary function of the metacarpophalangeal joints of the fingers is to aid in the gripping function of the hand. The articular cartilage of the metacarpophalangeal joints of the fingers is susceptible to damage, which, if left untreated, will result in arthritis with its associated pain and functional disability. Osteoarthritis is seen in the metacarpophalangeal joints of the fingers, which results in pain and functional disability, with rheumatoid arthritis, posttraumatic arthritis, and crystal arthropathy also causing arthritis of the metacarpophalangeal joints of the fingers. The metacarpophalangeal joints are commonly damaged by rheumatoid arthritis that causes a characteristic deformity as compared to the distal interphalangeal joints, which are more commonly affected by osteoarthritis (Fig. 79.2). Less common causes of arthritis-induced pain of the metacarpophalangeal joints of the fingers include the other collagen vascular diseases, infection, villonodular synovitis,
and Lyme disease. Acute infectious arthritis of the metacarpophalangeal joints of the fingers joint is best treated with early diagnosis, with culture and sensitivity of the synovial fluid, and with prompt initiation of antibiotic therapy. The collagen vascular diseases generally manifest as a polyarthropathy rather than a monoarthropathy limited to the metacarpophalangeal joints of the fingers, although pain of the metacarpophalangeal joints of the fingers secondary to the collagen vascular diseases responds exceedingly well to ultrasound-guided intra-articular injection.

Patients with pain of the metacarpophalangeal joints of the fingers secondary to arthritis, gout, synovitis, and collagen vascular disease-related joint pain complain of pain that is localized to the head of the metacarpals. Activity, including grasping motions, makes the pain worse, with rest and heat providing some relief. The pain is constant and characterized as aching in nature. Sleep disturbance is common with awakening when patients roll over onto the affected hand. Some patients complain of a grating, catching, or popping sensation with range of motion of the joints, and crepitus may be appreciated on physical examination.

Functional disability often accompanies the pain of rheumatoid arthritis affecting the metacarpophalangeal joints. Patients will often notice increasing difficulty in performing their activities of daily living and tasks that require grasping or pinching objects such as opening a jar or turning a doorknob. If the pathologic process responsible for pain of metacarpophalangeal joints of the fingers is not adequately treated, the patient’s functional disability may worsen, and muscle wasting and ultimately frozen metacarpophalangeal joints of the fingers joint may occur.

Plain radiographs are indicated in all patients who present with pain of the metacarpophalangeal joints of the fingers (Fig. 79.3). Based on the patient’s clinical presentation, additional testing may be indicated, including complete blood cell count, sedimentation rate, and antinuclear antibody testing. Magnetic resonance imaging or ultrasound of the metacarpophalangeal joints of the fingers joint is indicated if fracture, effusion, tendinopathy, crystal arthropathy, joint mice, synovitis, bursitis, or ligamentous injury is suspected (Fig. 79.4).